You hear the frequency difference between the switching freqs of the two amp modules. This is quite usual. In fixed freq PWM they usually sincronise the two freqs, or tune them at least 20kHz apart. But due to self-oscillating topology the sw freq changes (from lots of factors), so this way is only part possible here.
First you should check supply lines filtering. What do you use to filter the supply lines?
Then you should check ground connectiong. Either star grounding the two separate main ground planes, or one big groundplane could be the solution. How do you connect the grounds of the two amps?
I would suggest to swap the order (GND is the most important potential in every amplifier), but basically I agree!
What do you plug off? Input? Output? If input, then only signal line, or shield connection also? You can try to connect only shield without signal, or signal connected directly to shield. If this brings back beep, then there is a ground loop problem!
The best solution for this kind of problem are independent power supply (and GND) rails. But an excellent PCB layout, with much capacitors (like one of hypex) is much less sensible for this kind of interference.
Open cores (air core, single gapped toroids) of output filters can also be a source of this kind of problems, if they are near each other.
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burn mosfet
i use this lycanlk pcb.when i test -+40V its burn my mosfet.why this happen?i use irfp250.2 pair was already burn.its class d more sensitive from ab?because when i want check amp work or not i will touch input with my finger.if sound like thummmmmmm so my amp work.so what happen to my amp now?what my mistake.
second question.now i lost my irfp240.i heard can use irf540.what optimal and maximum for this fet?
i use this lycanlk pcb.when i test -+40V its burn my mosfet.why this happen?i use irfp250.2 pair was already burn.its class d more sensitive from ab?because when i want check amp work or not i will touch input with my finger.if sound like thummmmmmm so my amp work.so what happen to my amp now?what my mistake.
second question.now i lost my irfp240.i heard can use irf540.what optimal and maximum for this fet?
First of all, try to understand how class-D work. If you have no switching power knowledge and expereience, then yes class-d is more sensitive, and it is much harder to design.
Did you adjusted dead-time with RD-network? What is you output inductor?
Is this amplifier (Mosfet driven) advisable for use on subwoofers around 500watts rms each? I'm really wondering if this is the case, why are most professinal amps are not MOSFET?
I'm planning to build this one but also considering bipolar-junction transistor amps but still i cant decide which to make.
I'm planning to build this one but also considering bipolar-junction transistor amps but still i cant decide which to make.
This amp makes me headache....
- If Im using 20 K pot for Volume control highs will gone...
- I im add in seriell resistor in signal input to reduce sensivity high are less...
- Im im playing music amp is very noisy
- If Im using soundblaster extreme audio soundcard impossibile to listen with UCD amp fullrange music ---UCD very noisy
- If I connect input with 20k resistor to GND...no noise
- Did make test with NE5532 Op as input buffer to Lm311
forget it....high frequency noise
WITH NMOS DIY amp I dont have any noise
Did somebody use this UCD amp fur fullrange and can share schematric to solve problem ?
Attachment my PCB with groundplane
- If Im using 20 K pot for Volume control highs will gone...
- I im add in seriell resistor in signal input to reduce sensivity high are less...
- Im im playing music amp is very noisy
- If Im using soundblaster extreme audio soundcard impossibile to listen with UCD amp fullrange music ---UCD very noisy
- If I connect input with 20k resistor to GND...no noise
- Did make test with NE5532 Op as input buffer to Lm311
forget it....high frequency noise
WITH NMOS DIY amp I dont have any noise
Did somebody use this UCD amp fur fullrange and can share schematric to solve problem ?
Attachment my PCB with groundplane
Might be an earthing problem ?
Try adding an earth or disconnecting one.
The problems with the inpuit pot could be to do with the amp having a low input impedance.
I had similar problem with a irs2092 amp that has 3k3 input impedance.
Try adding an earth or disconnecting one.
The problems with the inpuit pot could be to do with the amp having a low input impedance.
I had similar problem with a irs2092 amp that has 3k3 input impedance.
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I dont know where and what ?
Who does use this amp for fullrange without any noise and can help
attachment my schematic
There is usually a connection from zero volts to earth.
Sometimes this can cause a ground loop and generate noise.
I always put a switch on mine becasue it depends what else is connected and if it is earthed or not.
I have also seen problems with mp3 players with poor mains supplies causing a lot of noise.
hey have add 1 uf capacitor in input stage and noise is gone and all highs and mids too...this is not the solution
Do you mean disconnect input GND from GND add in series 100 nf and connect to GND ?
But next problem...how to do high input impedance ..... to save my highs and mids
Can you share working schematic for perfect highs and mids ? I have not so much experience
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I don't think so. The root of the problem is not the schematic.
Don't you want to find the source of the noise?
Earlier you said you connected PC to amp directly, and it worked perfectly. If this is true (is it still true?), then all you had to make is an attenuator (= 1 potentiometer). Do you say this attenuator generates noise? How loud is the noise when you set it to zero volume, and what if you set it to maximum?
Nobody adviced this.
I don't understand you, but I bet he didnt mean this way. Earth is the 3rd contact of a power plug, and the metal parts of the device connected to it.
No, this is not the task. High input impedance is not a requirement (not at all!), and also doesn't save your highs.
I have same problem, mids and highs are gone when input pot is on any position, on 98% too, but when he is on 100% (maximum) then muds and highs are back. What can i do to reslove this.
This noise problem is from begin, and now, after 1238 posts we still dont fix this problem.
We know if we use 4.7n on input stage, mids and highs are bad and if we use 1n they comes back but amp have a noise.
Any sugestion how we reslove this problem once and for all. Please, we wants mids and highs 🙂
This noise problem is from begin, and now, after 1238 posts we still dont fix this problem.
We know if we use 4.7n on input stage, mids and highs are bad and if we use 1n they comes back but amp have a noise.
Any sugestion how we reslove this problem once and for all. Please, we wants mids and highs 🙂